The present invention relates to a steel laminate gasket of a very thin type.
A conventional steel laminate gasket is constructed by laminating several plates, and is provided with a complicated sealing portion around a hole to be sealed. Consequently, it is difficult to manufacture a steel laminate gasket with light weight. Also, productivity of a steel laminate gasket is poor. As a result, a steel laminate gasket is expensive than other gaskets.
In a small engine, a gasket must be light in weight and manufactured at a low cost. However, a conventional steel laminate gasket is heavy and expensive. Therefore, a conventional steel laminate gasket is not usually used for a small size engine.
In U.S. Pat. No. 4,834,399, a gasket formed of two plates has been proposed, wherein an area around a hole is sealed by one or two sealing means formed on the plates. The gasket can securely seal around the hole as intended. However, the gasket is not suitable for sealing around a hole where a large force is applied, e.g. an engine with high compression ratio.
In U.S. Pat. Nos. 4,896,891 and 4,971,338, a gasket is formed of at least two plates, wherein a small bead formed on a lower plate is situated under a large bead formed on an upper plate to support the large bead. The gaskets as disclosed in the patents can provide relatively wide sealing area, but the gaskets are not so good where tightening pressure is not so highly applied near the hole to be sealed.
Accordingly, one object of the present invention is to provide a steel laminate gasket with wide sealing area suitable for securely sealing around a hole, to which tightening pressure is not so highly applied.
Another object of the invention is to provide a steel laminate gasket as stated above, which is light in weight and simple in structure.
A further object of the invention is to provide a steel laminate gasket as stated above, which can securely seal around a hole without concentrating sealing pressure at one portion.
A still further object of the invention is to provide a steel laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.